Since the recognition of acute hantavirus-associated
respiratory disease in the United States in May 1993, laboratory
evidence of acute hantavirus infection has been confirmed in 30
persons in the southwestern United States; 20 (67%) of these
persons have died. Of those 30 persons, 23 resided in the
four-corners region (14 in New Mexico, six in Arizona, and three in
Colorado). Previously reported cases outside the four-corners
states occurred in a Nevada resident (1) and a Texas resident (2),
neither of whom had traveled to the four-corners area, and a
resident of another state who had traveled to and presumably was
infected in the four-corners area (3). This report summarizes the
other four confirmed cases and describes two cases under
investigation; all of these cases occurred outside the four-corners
area during July 1992-August 1993.
Confirmed Cases

Louisiana. During June 1993, a 58-year-old Louisiana bridge
inspector who had not traveled to the four-corners area died
following an illness characterized by bilateral interstitial
infiltrates and hypoxemia. Polymerase chain reaction (PCR) evidence
of hantavirus infection was found in lung tissue, and nucleotide
sequence analysis of viral genetic material PCR-amplified from the
lung suggests the presence of a previously unrecognized hantavirus
most closely related to but distinct from both the Prospect Hill
virus and the virus circulating in the four-corners area.

Nevada. In August 1993, a 51-year-old central Nevada resident
rapidly developed bilateral interstitial infiltrates and hypoxemia
over 12 hours following a 6-day illness characterized initially by
fever, myalgia, nausea, and vomiting, which progressed to coughing
and shortness of breath. The patient, who developed high-titered
immunoglobulin M (IgM) antibodies to hantavirus, had not traveled
to the four-corners area. As of August 11, the patient remained
hospitalized.

California. Two cases have been confirmed in California. In
the first, in July 1993, a 27-year-old field biologist, who was
working on the eastern slope of the California Sierra Nevada
mountain range, had acute onset of an illness characterized by 2
days of fever, myalgia, and headache. The patient developed rapidly
progressive bilateral interstitial infiltrates and hypoxemia and
died the following day. Hantavirus infection was confirmed by IgM
serology, PCR, and a positive immunohistochemical stain for
hantavirus antigen on lung tissue. The second case was in a
29-year-old ranch worker on the California coast who died of
rapidly progressive respiratory failure during September 1992,
following 3 days of fever, myalgia, and cough. Recent immuno-
histochemical staining of preserved autopsy tissues revealed
hantavirus antigen. Neither person had recently traveled to the
four-corners area.
Other Investigations

CDC is assisting state health departments in other
investigations, including 1) a California man who had serologic
evidence of past hantavirus infection following recovery from a
hantavirus-compatible illness during April 1993 and 2) a
16-year-old Oregon youth in whom hantavirus antigen was identified
by immunohistochemical staining of lung tissue saved from autopsy
in July 1992. The California man, but not the Oregon teenager, had
traveled to a four-corners state during the month before onset of
illness.

Editorial Note

Editorial Note: Newly recognized cases of acute illness with
evidence of hantavirus infection in Louisiana, Nevada, and
California, along with previously recognized cases in Nevada and
Texas, further demonstrate that hantavirus-associated respiratory
illness is not confined to the four-corners area of the
southwestern United States. Distinctive hantavirus nucleotide
sequences have been identified from a person with acute illness in
Louisiana; this information, together with confirmation of human
disease in areas of Texas (2) and Louisiana outside the known range
of Peromyscus maniculatus (4) -- the implicated reservoir in the
four-corners area -- suggests the existence of an additional
hantavirus with a different rodent reservoir in the south central
United States (3,5,6). The continued occurrence of hantavirus
disease underscores the importance of minimizing risk for exposure
to rodents and their excreta. Interim recommendations for
hantavirus infection risk reduction have been developed (7). This
document contains specific recommendations for reducing rodent
shelter and food sources in and around the home, recommendations
for eliminating rodents inside the home and preventing them from
entering the home, precautions for preventing hantavirus infection
while rodent-contaminated areas are being cleaned up, prevention
measures for persons who have occupational exposure to wild
rodents, and precautions for campers and hikers. Investigations of
cases of recognized and suspected human hantavirus disease and
potential rodent reservoirs are ongoing.

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